Mosquito habitat adaptation
My research interests center on understanding mechanisms of phenotypic evolution in natural populations. I am particularly interested in investigating how interactions between ecological forces and genetic mechanisms lead to evolutionary change. My approach to these broad questions is necessarily integrative, and utilizes field ecology, quantitative and population genetics, and molecular biology. I have chosen to focus on container-breeding mosquitoes as a model because these mosquitoes represent highly tractable experimental systems.
Modeling of the spread and distribution of infectious disease
We research and develop quantitative tools such as network theory to predict the spread and distribution of infectious diseases in human and livestock populations. We are particularly interested in the impact of specific population structures on the consequences of disease spread, the design of effective and practical intervention strategies, the evolution that results from the interaction between host populations and pathogens, and the effect of this interaction on the epidemiology of the disease. Some of the systems we study are influenza in humans and foot-and-mouth disease in livestock.
My main research work is in biodiversity, alien species and the ecology of arthropods. Students and I are working on the arthropods of Dyke Marsh Preserve of the National Park George Washington Memorial Parkway. Several recent field studies include alien invasive plant species and soil arthropods.
Population Genetics and Molecular Evolution
I am deeply intrigued by the processes that influence the distribution of genetic variation within species. My empirical projects focus on either marine fish populations or plant populations. Research in my laboratory focuses on fundamental questions in evolutionary biology, population genetics, and conservation genetics. I am interested in gene flow and population structure, the interplay of effective population size and natural selection, and inferring population demographic histories from genetic data. I frequently use simulation modeling to develop expectations for the behavior of genetic systems under idealized evolutionary processes. My lab also employs molecular genetic methods such as microsatellite genotyping and DNA sequencing to estimate key population genetic parameters such as effective population size, degree of population structure and rates of gene flow.
Sarah Stewart Johnson
The lab’s research is driven by the underlying goal of understanding the presence and preservation of biosignatures within planetary environments. We are currently investigating multiple Mars analog sites, from silica sinters and acid salt lakes to ancient deposits in the Dry Valleys of Antarctica, all with distinctive features that offer insights into what aqueous environments may have been like on the Red Planet a few billion years ago. Current projects focus on how life survives in extreme depositional environments, the persistence of lipid biomarkers over ancient timescales, and the ways in which biology affects patterns of mineralization. We’re also involved in the implementation of planetary exploration, analyzing data from current spacecraft and devising instrumentation for future missions.
My research in Shark Bay, Australia, began with a longitudinal study, the Dolphin Mother-Infant Behavioral Ecology Project, initiated in 1988. We’ve studied over 80 calves born to 60+ mothers and are examining a number of problems concerning calf development, female reproduction, genetics, ecology and behavior. I am generally interested in why bottlenose dolphins have such slow life histories, why females invest substantially in each calf, and what factors predict female reproductive success. These questions have both theoretical and applied (conservation and management) value.
Study of large-scale patterns of insects, mostly butterflies
Leslie Ries is an ecologist who focuses on patterns at both medium and large scales. She has worked both in the fields of landscape ecology and biogeography with her focus mainly on butterflies. Her current research focuses on large-scale patterns. She explores underlying mechanisms using laboratory studies of caterpillar growth and development based on different temperature regimes. She then studies these patterns across ranges using large databases, mostly originating from citizen science monitoring networks. Citizen science greatly expands the scale at which we can collect data and thus explore problems and solutions that are increasingly global in nature. Ries focuses on several facets of citizen-science, including the use of these data to answer large-scale ecological questions, especially those related to climate and land cover; developing statistical tools to extract the most robust information from the data; designing systems to support data management, visualization, and sharing; and developing “knowledge” databases that compile life history and other trait data to enrich multi-species analyses. In addition to carrying out and enabling large-scale ecological research, Ries has also been working on methods to integrate big-data approaches into undergraduate education, and she is also increasingly interested in informal education opportunities as well.
My research focuses on the role of behavior, by both plants and insects, in mediating interactions among the two groups of organisms. The sensory and behavioral attributes of insects, including vision, taste, smell, and touch, as well as a capacity to learn and remember, ultimately shape the insects' ability to interact with and exert selection on plants and on other insects. Similarly, the active 'behavior' of plants allows them to take advantage of insects' sensory and behavioral capabilities.
My research seeks to discover general rules that govern arthropod community structure that may serve as tools for conservation. I have found that plant genetics plays a critical role in shaping arthropod community structure, but the extent to which plant genetics affects higher-level trophic interactions remains a topic of debate which I am pursuing. My research also focuses on the role of anthropogenic disturbance and habitat fragmentation on arthropod community structure in inter-tidal marshes. I am using stable isotope analysis to understand how arthropod species losses in the inter-tidal marsh may affect nutrient cycling in these critical ecosystems that act as buffers to adjacent estuaries. Arthropod conservation has not received the same consideration as vertebrate species conservation, yet arthropods represent over half of the described species on the planet and their losses could have cascading effects throughout diverse ecosystems.